Cross-sectional associations between body fat and its distribution and environmental factors influencing energy balance were examined in 5115 young adults. Protein was directly associated with body mass index (BMI) in all race and sex groups (P less than 0.01) after age, education, cigarette-smoking status, alcohol intake, and physical activity were adjusted for. Carbohydrate intake was inversely associated with BMI in males (P = 0.02). Total physical activity was inversely associated with BMI in white women and with skinfold-thickness measures (P less than 0.01) in all groups. Waist-to-hip-circumference ratio (WHCR) was positively associated with total kilojoules (kilocalories) in women, inversely associated with percent of kilojoules (kilocalories) from carbohydrates in whites, grams of crude fiber/4184 kJ (1000 kcal) (except in black men), and physical activity (except in white women). WHCR was directly associated with cigarette smoking except in black men, and with total alcohol intake in men. Beer was consistently associated with WHCR in all race and sex groups.